Method of coupling styrene with alkyl aromatics



States Patent METHOD OF COUPLING STYRENE WITH ALKYL AROMATICS Charles E. Frank,i;Cincinnati, Ohio, and James S. Swinehart, Brooklyn, N. Y., assignors to National Distillers Products Corporation, New York, N. Y., a corporation .of Virginia No Drawing. Application June 16, 1954, Serial No. 437,305

7 Claims. (Cl. 260-670) rial, a suspension of alkali metal which is preferably sodi- This suspension may be prepared by mechanical mixing of the alkylaromatic and the alkali metal at a temperature above the melting point of the metal, preferably in a colloid mill or other dispersion apparatus and, preferably in the presence of agents such as sodium oleate, aluminum stearate, pyridine and the silicone oils which facilitate the forming of stable dispersions of alkali metal. Alternatively, the reaction mixture may be formed by adding to the alkyl aromatic a preformed suspension of alkali metal in a hydrocarbon solvent.

The'dispersion of alkali metal and alkyl aromatic is held at a temperature between 60 C. and 200 C., and preferably at a temperature between 120 C. and 160 C., and, while so held, the styrene is added gradually and preferably continuously and at a substantially uniform rate.- To promote the reaction, the dispersion should be vigorously mixed during the period while the styrene is being added; .For. best results the rate of addition should not exceed 0.25 moles of the styrene per hour per mole 5 of alkali :metal present in the dispersion. Preferably, the rate of styrene per hour per mole of sodium should be held below 0.15. The rate of addition of the styrene may therefore be increased by increasing the amount of alkalimetal present although there does not appear to be any further advantage in maintaining more than one mole of alkali metal for each mole of free alkyl aromatic present.

The temperature, rate of addition, amount and sub- Ice If desired, all the alkyl aromatic may be introduced at mum reacting conditions approach, as a limit, the presence of one mole of alkali metal for each mole of free alkyl aromatic present, this requires an excessive amount of alkali metal. It is, therefore, more elficient to start with a body of alkyl aromatic containing one mole of alkali metal for each 1 to 2 moles of alkyl aromatic prescut. The rate of addition of the styrene is determined by the amount of the alkali metal present, as above indicated. The critical ratio of styrene (free and combined)'t0 the total alkyl aromatic (free and combined) present at any time is maintained by adding the styrene in solution in the amount of alkyl aromatic required to maintain 5 to 8 moles of alkyl aromatic present in the system for each mole of styrene present at any time.

The alkali metal is preferably present in a state of extremely fine dispersion, i. e., predominantly in the form of droplets or dispersed particles having a maximum diameter not in excess of 50 microns.

The reaction temperature may be maintained in any suitable way. If the particular alkyl aromatic boils within the desired temperature range, control of the temperature is accomplished by refluxing. If it boils at too low a temperature, under normal pressures, this can be corrected by the application of pressure in excess of atmospheric to completely, whereupon the supernatant layer is decanted and distilled to separate the unreacted alkyl aromatic, following which the residue is distilled under reduced pressure to separate the various end products.

The entire reaction can be carried out continuously by the continuous addition to the system of styrene and alkyl aromatic, at substantially the same rate at which they undergo coupling reaction within the system, together with the amount of alkali metal necessary to maintain the reaction velocity, and by continuously abstracting a part of the reactants from the system, components, withdrawing the end products and returning the remaining alkali metal and unreacted alkyl aromatic to the system.

division of the alkali metal should be coordinated to insure the substantially immediate reaction of the styrene with the alkyl aromatic as it is added thereto. If the styrene does not react with the alkyl aromatics substantially completely as it is added, a polymerization of the styrene results which yields a large amount of styrene polymer rather than the desired coupled product. When operating using the critical conditions, the amount of polymer produced is negligible. In general, this result will be obtained by holding the total styrene (both free and combined) present in the system at any time to not more than one mole for each 5 moles of alkyl aromatic (free and combined) present, and preferably not more than The desired end products of the coupling reactions are valuable as chemical intermediates and may, inter alia, be sulfon'ated to yield highly efiicient wetting agents. The polymerized material obtained as by-products is substantially useless.

The following are typical examples of the application of the invention, although it is not intended to limit the invention strictly thereto.

Example I 330 cc. 2.7 g. moles) of ethylbenzene and 23 grams (1 g. atom) of sodium were maintained at a temperature of 137 C. under an atmosphere of dry nitrogen. The sodium was present in the form of relatively small droplets suspended in the liquid. The system was vigorously stirred to maintain the velocity of the reaction and to keep the.

onemol'e of styrene for each 8 ,moles of alkyl aromatic.

present. These values constitute the upper and lower limits of the ratio of total styrene to the totalalkyl aromatics which produce satisfactory operation.

sodium in suspension. 49 grams (0.47 g. mole) of styrene in 480 cc. (3.9 g. moles) of ethylbenzene was added to the system continuously and gradually, the addition of the total amount of styrene being extended uniformly over v a period of 8 hours. This corresponds to an additionv rate separating this into its ama s.-

'The resiglue (approximately 15% of the total volume) quenched; with; 60: cc. of: ethylv alhoh'oli and washed fliefiofgalkaiih Aftendryingit wa'szdistilled undernredueeipressurm, The followingadditionallprodnetsewem bta ned? a 5.3.:- l hen l ntane. 7 t m7 Lfiafii ipheny heaane. 2:9. elt/men a '3' Example I1 9 mm- (lzmolesi f rmtzthy n nhthalen andd8t5tg. GIT-Sig. atom) 0. odi m d pers d t 8-;5.g-=Qfi 1 211 8: lene were mai ntainedat a temperatureofi150,?104 60 C. under. an atmosphere 0f dry nitrogen; The sodiurm was; the form of, droplets. predominantly not; in; excess; of. 50 microns in diameter. The system was vigorously; stirred;. to, maintainlhe velocity of -the reaction.- v 20.- grams 1191 moles of." styrene, dissolved in 20 0 -cc.- (1.4 moles) of wm'ethylnaphthalene, was added gradually, ,the;-rate 0faddi tionBeing,suhstantiallyuniform over a 7 hounperiod; 'I'IiisIePIesentsLan addition rate.of .03 mole of; styrene; per mole of'sodium penhour. 60 cc. of 90% :ethylalco; oLwa fih nad j d'to q qh nym sq i m sent following which-the material was washed freeof alkali andldistilled under-reduced pressure. The following yields wereobtainedi G2 l-phenyl-i-(u naphthyltpropane) 2825 Polymer- Example 111 1 3-1Ql 6% O ;%R- Iy1ene:,andq;50; gm of. were mailratallied ag temperaturetoi-l39f Qaunderz' an: atmosphere:. Ofdry nitrogen The sodium,waspresentyin:the:forn1:;of: lat yeln 11 LQlflfits: and: the:system..waswigorouslye stirred-Jo malnt n;.the velocityijofzthe'reactiomand:keep.

'of 'dry nitrogen. The organic and water layerszwerezthenzw n tee n ilh i .o sanielayend stilledt Thetfollowin wee a e-' b a ned-z I U Ext emal-V 140Zg1'ams of 'ethylhenzeneand 25 -gram's'of 'so'cliutn irr the. fomrofsa dispersion, the-particles ofwhich wel'gfpl'gy dominantly not in excess of 50- microns in' diameter; was maintainsd1 atza' temperatureof137?- The system was vigorously stirred to maintain the' veloei-t'y QFthereactiQn' andi62- gramskofistyrene'dissolved-in 1760' grams; of eflrylbenzene w'a's a'dded -gradually; the-rate o*'='a'ddition pr ses substantially un c m f r a 1 heat m nd. The tyreneadditibn was at the rate of .035 mole of styrene per mole of sodium per hour. The sodium was then quenched by the addition of water under an atmosphere of dry nitrogen. The organic and waterlayers were separated and the organic layer distilledl The following yields were obtained: 7

Condensation produet of; 1}. molecule of ethylhem zene. with 2 molecules. of styrene: 922 Polymer 1&2

Example. W i

cc. of ethylbenzeneand23'grams of sodium were maintained at a temperaturezoffi l3:7;fQ;' .1mder an atmosphere of dry nitrogen. The sodium was present in the form of, relatively smalltdroplets and the; system wasvigorously stirred to maintain thezyelocityrofireactiom ancltokeep thesodiumdropletsin suspension, 49! grams ofifstyrenedisjsolyed in 69.01ec. of'ethylhenzene wasadd'ed.

to thesystem continuously, the addition. of, the.- 'total amount of 'styrene.heingextendediunifhrmly over atperi di of 8- hours. ,styrene addition rate is. .06. mol'emf'" styrene penmole. ofsodiurntper hour. The remaining-so: dium was then que'nched'hy the addition ofwater under an .atmospl1ere ofdry, nitrogen. Theorganic and water layers wereseparated jandjthe organic Iayer distiIIedI The followingyieldswereohtained? GT. 1,3'-diplfeuylbutane p t 7 65M" Condensation prod, ctlofjlmolecule of .etliylbenzene. p

with 2i'molecu1esof styrene Polymer 3221 Example l-Vli In' one experiment; styrene (i52'grams'); dissol ed"in"' mole percent of the styrene used) in'ZOO' gramsofethyl-f benzene; While? maintaining the temperature" at 1-37 6.

This' isgaf styrene addition rate of .12 moleof styrene'perf mole 0f1sodium-p 7rthour; Theprodueticomprisedifii /lv 17v hour periddito a=-'stirred suspension" of 'l3.8 grams=of"" sodium ;(equivalent torthe styrene usedd inQO'D grams of} ethylb enzene-while maintaining' the temperature at*; 137

' a, styrene addition rate of .06 mole per mble oi soidium-perhoun Tlie" '1'n o'd'uct comprised*-' 67% oftlie theoretiaP-yild? of "'1i3 'ctiitalietmlli'utame}- remainder "of theeproduct beihgf-higher moleeular weight material's? Samples removed iiom thereaetiom miXmre afier peri'eds of Wand -1fi hoursshowecf' lessthaw-1 of the added styrene present in the uncombined form. The amount* of uncombined styrene was d'etermii1e'd By the;

C3? This represents iodinwnumber:

' Exampi -VH Staten; (52.; grams); dissolyed eonz m o aa y benzene wasgaddfiimuer a. .7. hour periodlto.,.a.; stii'r benzene wliil'e ,,maintaihing the temperature. 137 'CLT ExempleizVflliu in satisfactory yields.

benzene containing grams of dispersed sodium was heated 5 hours at 137 C. Fractionation of the products yielded 2% of the theoretical 1,3-diphenylbutane; 98% of the styrene was converted to a glassy, fusible polymer.

What is claimed is:

1. A method of coupling styrene with alkyl aromatics which comprises maintaining a body of alkyl aromatics containing dispersed alkali metal in the form of suspended droplets having a diameter not greater than microns, at a temperature betweein and 200 C., and adding styrene thereto at a substantially uniform rate not greater than 0.25 mole of styrene per hour per mol of alkali metal present in the reacting mixture, maintaining an amount of alkali metal at all times during the reaction period of at least 1 mole of alkali metal to 10-12 moles of alkyl aromatics (both free and combined), and maintaining the mole ratio of total styrene (both free and combined) to total alkyl aromatics (both free and combined) to a ratio not exceeding 1 to about 5.

2. A method according to that described in claim 1 in which the temperature is maintained between and C.

3. A method of coupling styrene with alkyl aromatics which comprises maintaining a body of alkyl aromatics containing dispersed sodium in the form of particles having a diameter not greater than 50 microns, at a temperature between 60 and 200 C., and adding styrene continuously and uniformly thereto at a rate not greater than 0.25 mole of styrene per hour per mol of sodium present in the reacting mixture, maintaining an amount of sodium at all times during the reaction period of at least 1 mole of sodium to 10-12 moles of alkyl aromatics (both free and combined), and maintaining the mole ratio of total styrene (both free and combined) to total alkyl aromatics (both free and combined) to a ratio not exceeding 1 to 5.

4. A method of coupling styrene with alkyl aromatics which comprises maintaining a body of alkyl aromatics containing dispersed sodium in the form of suspended styrene in solution in additional alkyl aromatics at a substantially uniform rate not greater than 0.25 mole of styrene per hour per mol of sodium in the reacting mixture, the rate of styrene addition at no time substantially exceeding the rate of styrene reaction, maintaining the mole ratio of sodium to total alkyl aromatics at all times during the reaction period between 1 to 1-2 and 1 to 10-12, and maintaining the mole ratio of total styrene (both free and combined) to total alkyl aromatics (both free and combined) to a ratio not exceeding 1 to 5.

5. A method according to that described in claim 4 ,7

in which the temperature is maintained between 120 and 160 C.

6. A method of coupling styrene with alkyl aromatics which comprises maintaining a body of alkylaromatics containing dispersed sodium in the form of suspended droplets having a diameter notgreater than 50 microns at a temperature between 120 and 160 C.,' and continuously adding styrene in solution in additional alkyl aromatics at a substantially uniform rate not greater than 0.15 mole of styrene per hour per mol of sodium in'the reacting mixture, the rate of styrene addition at no time substantially exceeding the rate of styrene reaction, maintaining the mole ratio of sodium to total alkyl aromatics at all times during the reaction period between 1 to 1-2 and 1 to 10-12, and maintaining the mole ratio of total styrene (both free and combined) to total alkyl aromatics (both free and combined) to a ratio not exceeding about 1 to 5.

7. A method, as defined in claim 6, wherein the alkyl aromatic is a member from the group consisting of ethylbenzene, oz-methylnaphthalene, and para-xylene.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A METHOD OF COUPLING STYRENE WITH ALKYL AROMATICS WHICH COMPRISES MAINTAINING A BODY OF ALKYL AROMATICS CONTAINING DISPERSED ALKALI METAL IN THE FORM OF SUSPENDED DROPLETS HAVING A DIAMETER NOT GREATER THAN 50 MICRONS, AT A TEMPERATURE BETWEEN 60* AND 200* C., AND ADDING STYRENE THERETO AT A SUBSTANTIALLY UNIFORM RATE NOT GREATER THAN 0.05 MOLE OF STYRENE PER HOUR PER MOL OF ALKALI METAL PRESENT IN THE REACTING MIXTURE, MAINTAINING AN AMOUNT OF ALKALI METAL AT ALL TIMES DURING THE REACTION PERIOD OF AT LEAST 1 MOLE OF A ALKALI METAL TO 10-12 MOLES OF ALKYL AROMATICS (BOTH FREE AND COMBINED), AND MAINTAINING THE MOLE RATIO OF TOTAL STYRENE (BOTH FREE AND COMBINED) TO A TOTAL ALKYL AROMATICS (BOTH FREE AND COMBINED) TO A RATIO NOT EXCEEDING 1 TO ABOUT
 5. 